<!DOCTYPE html>
<html>
<head>
    <title>贪吃蛇</title>
    <meta charset="UTF-8">
    <meta name="keywords" content="贪吃蛇">
    <meta name="Description" content="这是一个初学者用来学习的小游戏">
    <style type="text/css">
    *{margin:0;}
    .map{margin:100px auto;
        height:600px;
        width:900px;
        background:#00D0FF;
        border:10px solid #AFAEB2;
        border-radius:8px;
    }
    </style>
</head>

<body>
<div class="map">
<canvas id="canvas" height="600" width="900">

</canvas>
</div>

<script type="text/javascript">
 //获取绘制工具
    /*
    var canvas = document.getElementById("canvas");
    var ctx = canvas.getContext("2d");//获取上下文
    ctx.moveTo(0,0);
    ctx.lineTo(450,450);*/
    var c=document.getElementById("canvas");
    var ctx=c.getContext("2d");
    /*ctx.beginPath();
    ctx.moveTo(0,0);
    ctx.lineTo(450,450);
    ctx.stroke();
    */

    var snake =[];//定义一条蛇，画蛇的身体
    var snakeCount = 6;//初始化蛇的长度
    var foodx =0;
    var foody =0;
    var togo =0;
    function drawtable()//画地图的函数
    {


        for(var i=0;i<60;i++)//画竖线
        {
            ctx.strokeStyle="black";
            ctx.beginPath();
            ctx.moveTo(15*i,0);
            ctx.lineTo(15*i,600);
            ctx.closePath();
            ctx.stroke();
        }
        for(var j=0;j<40;j++)//画横线
        {
            ctx.strokeStyle="black";
            ctx.beginPath();
            ctx.moveTo(0,15*j);
            ctx.lineTo(900,15*j);
            ctx.closePath();
            ctx.stroke();
        }

        for(var k=0;k<snakeCount;k++)//画蛇的身体
            {
            ctx.fillStyle="#000";
            if (k==snakeCount-1)
            {
                ctx.fillStyle="red";//蛇头的颜色与身体区分开
            }
            ctx.fillRect(snake[k].x,snake[k].y,15,15);//前两个数是矩形的起始坐标，后两个数是矩形的长宽。

            }
            //绘制食物  
            ctx.fillStyle ="black";
         ctx.fillRect(foodx,foody,15,15);
         ctx.fill();

    }


    function start()//定义蛇的坐标
    {
        //var snake =[];//定义一条蛇，画蛇的身体
        //var snakeCount = 6;//初始化蛇的长度

        for(var k=0;k<snakeCount;k++)
            {
                snake[k]={x:k*15,y:0};

            }

          drawtable();
          addfood();//在start中调用添加食物函数

    }

    function addfood()
    {
    foodx = Math.floor(Math.random()*60)*15; //随机产生一个0-1之间的数
    foody = Math.floor(Math.random()*40)*15;

        for (var k=0;k<snake;k++)
        {
            if (foodx==snake[k].x&&foody==sanke[k].y)//防止产生的随机食物落在蛇身上
            {   
            addfood();
            }
        }


    }   

   function move()
   {
    switch (togo)
    {
    case 1: snake.push({x:snake[snakeCount-1].x-15,y:snake[snakeCount-1].y}); break;//向左走
    case 2: snake.push({x:snake[snakeCount-1].x,y:snake[snakeCount-1].y-15}); break;
    case 3: snake.push({x:snake[snakeCount-1].x+15,y:snake[snakeCount-1].y}); break;
    case 4: snake.push({x:snake[snakeCount-1].x,y:snake[snakeCount-1].y+15}); break;
    case 5: snake.push({x:snake[snakeCount-1].x-15,y:snake[snakeCount-1].y-15}); break;
    case 6: snake.push({x:snake[snakeCount-1].x+15,y:snake[snakeCount-1].y+15}); break;
    default: snake.push({x:snake[snakeCount-1].x+15,y:snake[snakeCount-1].y});
    }
    snake.shift();//删除数组第一个元素
    ctx.clearRect(0,0,900,600);//清除画布重新绘制
    isEat();
    isDead();
    drawtable();
   }            

   function keydown(e)
   {
   switch(e.keyCode)
        {
         case 37: togo=1; break;
         case 38: togo=2; break;
         case 39: togo=3; break;
         case 40: togo=4; break;
         case 65: togo=5; break;
         case 68: togo=6; break;
        }
   }

   function isEat()//吃到食物后长度加1
   {
    if(snake[snakeCount-1].x==foodx&&snake[snakeCount-1].y==foody)
   {
        addfood();
        snakeCount++;
        snake.unshift({x:-15,y:-15});
   }

   }
   //死亡函数
   function isDead()
   {
    if (snake[snakeCount-1].x>885||snake[snakeCount-1].y>585||snake[snakeCount-1].x<0||snake[snakeCount-1].y<0)
        {


        window.location.reload();
        }
   }

    document.onkeydown=function(e)
{
    keydown(e);

} 
window.onload = function()//调用函数
{ 
    start();
    setInterval(move,150);
    drawtable();



}
</script>
</body>
</html>

